1 /* 2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_G1_G1FIXEDSIZESTACK_INLINE_HPP 26 #define SHARE_VM_GC_G1_G1FIXEDSIZESTACK_INLINE_HPP 27 28 #include "gc/g1/g1FixedSizeStack.hpp" 29 #include "runtime/atomic.inline.hpp" 30 #include "runtime/orderAccess.inline.hpp" 31 #include "utilities/debug.hpp" 32 33 size_t G1FixedSizeStackBase::length() const { 34 return OrderAccess::load_acquire((volatile intptr_t*)&_length) & LengthMask; 35 } 36 // This is required for the use of Atomic::cmpxchg_ptr in par_push(). 37 STATIC_ASSERT(sizeof(intptr_t) == sizeof(size_t)); 38 39 template <class T> 40 void G1FixedSizeStack<T>::par_push(const T elem) { 41 // Try to set exclusive access to the length field by setting its upper bit. 42 size_t cur_length = length(); 43 while (true) { 44 size_t old_length = (size_t)Atomic::cmpxchg_ptr((intptr_t)cur_length | nth_bit(BitsPerWord - 1), (volatile intptr_t*)&_length, (intptr_t)cur_length); 45 if (old_length == cur_length) { 46 assert((cur_length & nth_bit(BitsPerWord - 1)) == 0, "Topmost bit must not be set in old value."); 47 break; 48 } 49 cur_length = old_length & LengthMask; 50 } 51 assert(cur_length < _max_length, "Tried to push more objects than there is space."); 52 set_by_index_raw(cur_length, elem); 53 OrderAccess::release_store_ptr((volatile intptr_t*)&_length, cur_length + 1); 54 } 55 56 #endif /* SHARE_VM_GC_G1_G1FIXEDSIZESTACK_INLINE_HPP */